| Hypersonic vehicle can realize ultra-long-distance flight,fast strike and long-distance delivery,and can greatly expand the battlefield space,due to its fast speed and strong penetration capability.It has unique advantages for information collection,reconnaissance,surveillance and communication support.But it also has the characteristics of strong nonlinearity,strong coupling and strong uncertainty,which brings great difficulties to the design of its control system.In this paper,the design of control system for the typical longitudinal in-plane of hypersonic vehicle is studied.Aiming at two different hypersonic vehicle models,an applicable design method of longitudinal trajectory tracking control system is proposed,which can be used to solve the problem of the uncertainty,non-minimum phase,engine performance recovery and evaluation and optimization for control system of hypersonic vehicle,achieving high precision and strong robustness tracking control effect.The main research work of this paper includes the following contents:Firstly,two types of hypersonic vehicles,Winged-cone and Quasi wave-rider,are introduced,and their longitudinal dynamics models are given respectively.Under the condition of hypersonic flight,the stability,aero-thrust coupling and non-minimum phase characteristics are analyzed.Based on the analysis results,the design requirements of hypersonic vehicle control system are described.A finite-time convergent trajectory tracking control method based on Differential Flatness theory is proposed for the longitudinal model of Winged-cone hypersonic vehicles.By Using Differential Flatness theory,the nonlinear model is transformed into an input/output linearized model consisting of flat outputs.The whole process states and control inputs of the system can be expressed by flat output and its finite order differential.The reference trajectory validation considering state constraints and control capability is realized.Then,based on the finite-time theory,a finite-time convergent sliding mode controller is designed to realize the finite-time tracking of the longitudinal trajectory of Winged-cone hypersonic vehicles.A longitudinal trajectory tracking control method based on Byrnes-Isidori normalized form is proposed for the longitudinal model of Quasi wave-rider hypersonic vehicle considering its nonminimum phase characteristics.Through coordinate transformation,the nonminimum phase model is transformed into Byrnes-Isidori normalized form,and the internal and external dynamics of the system are obtained.Based on the standard form,the quantitative criterion for nonminimum phase characteristics of the longitudinal model of Quasi wave-rider hypersonic vehicle is given.A sliding mode controller is designed for the minimum phase velocity subsystem and a dynamic integral sliding mode controller is designed for the nonminimum phase flight path angle subsystem.In particular,the dynamic sliding mode control method transforms the flight path angle subsystem into an augmented system composed of internal and external dynamics and regulators,which makes the closed-loop poles adjustable,effectively improves the tracking performance of the system,and stabilizes the internal dynamics of the system.Considering the working conditions of the scramjet,the guaranteed performance control method and the performance recovery control scheme of the Quasi wave-rider hypersonic vehicle are proposed.Firstly,the working conditions of the engine are analyzed,and the lower speed limit of the vehicle in the reasonable range of angle of attack is obtained.Based on the logarithmic barrier function,a speed guaranteed control method is proposed with the lower speed limit as the state constraint of the vehicle.Then,considering the unexpected engine flameout,as the engine is the only available control input for vehicle acceleration,once the engine flameout occurs,the vehicle will continue to decelerate and can not recover the desired speed tracking.Therefore,this paper strategically adopts temporary trajectory adjustment to restore the speed of the vehicle.When the speed restores to an acceptable range,the control angle of attack reaches the restart value and the engine restart is completed.After the engine restores its propulsion performance,the desired trajectory can be tracked again.Aiming at the control system optimization problem of hypersonic vehicle with complex flight mission,a control system optimization method of hypersonic vehicle based on performance evaluation is proposed.Firstly,according to the system structure and mission requirements of hypersonic vehicle,the performance evaluation index system of hypersonic vehicle is established.Then,considering the problem that the local performance of hypersonic vehicle may be submerged after synthesis,a performance evaluation method of variable weight attribute hierarchical model is proposed.When the local performance of hypersonic vehicle is poor,the hypersonic vehicle with local weight enlargement penalty is realized.Aiming at the optimization problem of control system and considering the optimization efficiency of cycle simulation,an intelligent particle swarm optimization algorithm with variable optimization range is proposed to achieve the balance and trade-off between optimization performance and optimization efficiency.Finally,with the aid of the hypersonic vehicle performance evaluation and optimization assistant tools,the comprehensive performance evaluation of the control system is carried out,and the performance optimization of the control system of the hypersonic vehicle with complex flight mission is completed.In summary,the longitudinal trajectory tracking control of two types of hypersonic vehicles is systematically studied in this paper.The uncertainties,non-minimum phase problems,engine performance recovery problems,performance evaluation and optimization problems have been studied and some research progress has been made,which supplements the existing research results and provides necessary technical support for the control of hypersonic vehicle. |
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